It is previously known to arrange controlled (alt. non-controlled) output yarn braking on yarn feeders. A known brake uses a spring member which is applied over the yarn path with one or more eye-shaped parts which can be tightened and slackened by means of the control member acting on the ends of the spring member. On tightening/slackening, the pressing against the yarn and the counterstay surface is modified (see e.g. U.S. Pat. No. 4,785,855, FIGS. 4-7).
It is also known to arrange individual spring members which are placed around the periphery of the yarn-storing part of the storing body of the yarn feeder. The spring members are in principle secured at their first ends and bear with their free ends against the yarn and press the latter against the underlying surface on the yarn-storing part of the storing body of the yarn feeder (see e.g. U.S. Pat. No. 4,785,855, FIGS. 2 and 3).
It is already known to control such spring elements in order to produce a yarn-braking function in which the spring elements press the yarn to a greater or lesser extent against a peripheral surface on the spool body of the yarn feeder.
It is thus previously known to provide brake arrangements which modify the yarn tensioning during the respective pick in the weaving machine. For example, in a projectile weaving machine, the yarn tensioning (brake effect) will be low or zero at the start of the drawing-off process as the projectile accelerates to its maximum speed. Thereafter, the yarn tensioning (brake effect) should be increased in the brake arrangement on account of the fact that the projectile slows down in its movement towards its other end position, and the yarn balloon formed on the bearing body on account of the drawing-off function would otherwise, as a result of the mass and movement of the yarn, "catch up with" the yarn part running out from the brake arrangement and would cause problems in respect of the brake arrangement. It is therefore desired to adapt the yarn drawing-off (yarn tensioning) to the movement of the projectile in the weaving process. A number of proposals for solving this problem are already known.
For example, in gripper machines, it is desirable to be able to produce a half-wave sinusoidal variation of the braking function/yarn-tensioning function. The first gripper draws out the yarn during an acceleration stage which is followed by a deceleration stage so that the yarn speed upon changeover to the subsequent gripper member is virtually zero. Such a variation also causes problems, since the accelerated yarn mass at the drawing-off point on the storing body must be prevented from pressing against the brake-effecting parts and causing disturbances (entangling tendencies).
It is known to use a controlled brake/tension-generating unit of the type which comprises two surface-supporting parts which can be placed opposite each other and which can be mutually influenced in directions towards and away from each other and between which a thread part running out from the thread store of the thread-storing member is passed during the thread drawing-off from the said member. The first surface-supporting part is positioned at or on the end surface of the thread-storing member, or alternatively consists of a part of the said end surface, and the second surface-supporting part is arranged on a unit situated outside the said end surface.
It is also known to arrange a non-controlled brake for thread-storing members, and the known brake is in this case of the type comprising two surface-supporting parts which can be placed opposite each other and which can be mutually influenced in directions towards and away from each other and between which a thread part running out from the thread store of the thread-storing member is passed during the thread drawing-off. The first surface-supporting part is placed at or on the end surface of the thread-storing member and the second surface-supporting part is arranged on a unit situated outside the end surface.
The prior art inventions relate to a controlled or a non-controlled brake-/tension-generating unit for a thread-storing member, preferably a yarn feeder on a textile machine, for example a weaving machine, and can in this respect be of the type comprising two surface-supporting parts which can be placed opposite each other and which can be mutually influenced in directions towards and away from each other and between which a thread part running out from the thread store of the thread-storing member is passed during the thread drawing-off from the said member. The first surface-supporting part is placed at or on the end surface of the thread-storing member and the second surface-supporting part is arranged on a unit situated outside the end surface.
It is necessary for the brake to be able to function appropriately even on rapidly operating textile machines. For example, in weaving machines of the gripper type, the pick frequency can be 600 picks/min. or more. In addition, the brake will have to be able to effect a braking function which varies during the very quick drawing-out of the yarn. For example, in the case of gripper machines, it is desirable for the brake members to be able to provide a sinusoidal variation of the clamping force, or a variation of the clamping force adapted to the machine function.
It is also important for the brake function to be arranged at parts of the yarn feeder where the yarn drawing-off function is not disturbed and where the brake member does not unduly add to the periphery of the yarn feeder. It should be possible to obtain an effective control of the yarn at the drawing-off area for the yarn.
The known brake members do not solve the abovementioned problems. Brake members with eye-shaped parts which can be tightened and slackened are inexact on account of the fact that the tightening cannot be carried out uniformly around the whole periphery. The actuation of the known individual spring members with magnetic force which will give rise to the pressing of the spring members against the yarn when the latter passes under the spring members is too inexact and can only be used for purely so-called on-off functioning.
There is therefore a requirement to produce a pressing function (braking function) against the yarn, which function is varied during each drawing-off process of the yarn. There is also a requirement that it should be possible for the varied pressing function to be effected during rapid yarn drawing-off processes, and in this respect it may be mentioned that textile machines, for example gripper machines, can operate at high pick frequencies, for example 600 picks/min. or higher. The output yarn brakes known hitherto operate essentially with purely on-off functions, which may be suitable if the only requirement is to achieve braking during part of the drawing-out process, for example in the final part thereof. The importance of the requirement of obtaining a instantaneously varied braking function during the drawing-off process, for example sinusoidal variations of the pressing force, has not to data been appreciated.
It is a complicated technical problem to achieve a suitable braking or yarn-tensioning function which takes into account with sufficient accuracy the acceleration and deceleration processes which occur during the drawing-off of the yarn. The problem becomes greater with increasing speeds of the machines used. Yarn speeds of up to 30 m/s (6,000 rpm) may be encountered in the machines of today and of the near future. Brake arrangement functions which can adapt to such rapid drawing-off processes must be able to operate at brake movement frequencies of between 20 and 200 Hz.
The choice of diameter of the surface-supporting parts in relation to the diameter of the thread store can vary. The weight (mass) of the components forming part of the output brake certainly increases when the diameter of the surface-supporting parts does not deviate substantially from the diameter of the thread-storing member.
It is therefore important to make the brake function more effective at the output side of a thread-storing member. The arrangements concern, inter alia, effective methods and means for effecting a varied brake function/thread-tensioning function during one and the same draw-off, for example one and the same pick in a weaving machine.
It is also important, in equipment of this type, for thread-braking/thread-tensioning generators with different functions to be made available. In this respect, it will be possible in principle for the brakes to have the same basic construction, but it will be possible for them to be designed for manual setting of the brake/thread-tensioning value which in this respect will be able to be kept constant (non-controlled) during a predetermined use period/operation. Furthermore, it will be possible for the setting to be carried out by purely manual means and/or by electrical means.
The present invention aims to solve these problems too and gives details of effectively operating brakes/thread-tensioning generators in which set values for the thread tensioning can be maintained, or alternatively variations can be effected during the same thread draw-off in a rapid and effective manner. The new construction also makes it possible to arrange brakes in which the brake surfaces can be kept free of (textile) lint and the like as a result of the "rotating" movements of the thread in the brake during the draw-off from the thread-storing member. The surface-supporting parts can also be designed with braking or clamping surfaces which provide effective cooling during the thread drawing-off process.
To be more specific than the above, one embodiment of the invention may involve the surface-supporting parts having external diameters which are substantially reduced, for example 10-40% of the external diameter of the thread storing (from which drawing-off takes place).
In further embodiments of the concept of the present invention, further details are given regarding the construction of the brake unit. An important point in this respect is that it will be possible for low-weight brake members to be used.
There is a requirement for a superactive brake/yarn-tensioning arrangement which can react instantaneously to the passage of a knot or other irregularity where it is a question of yielding immediately to the knot/irregularity from an executed braking or tensioning function, so that a yarn break or inadmissibly high yarn tensioning, which may endanger the operation, does not occur. It will be possible for the arrangement to operate at times of the order of magnitude of milliseconds or less. The arrangement will also be able to return to its executed function (braking/tensioning) immediately after the passage within or after the said time period. In the case of controlled braking, the control will be able to take place during the same machine stroke or equivalent. A superactive brake/tensioning arrangement is necessary in this respect. Activation, i.e. engagement and disengagement, increase/decrease, etc., will be able to be effected within the time interval 0.1-1.0 ms, which presupposes quick and light mechanical systems and components.
The present invention aims, inter alia, to solve the problems mentioned above, and the features which may be regarded as characterizing the invention are the fact that the members mentioned in the introduction are designed so as to effect a yarn-cleaning function, dependent on yarn rotation upon drawing-off, while simultaneously preventing considerable accumulation of material to be cleaned (lint, particles, etc.) in respect of the members (9, 15), and the fact that a mobility obtained by means of the component and weight choice for the member(s), bearing(s) etc., and preferably by means of considerably reducing the size of the external dimension of the first member, provides an instantaneous (for example 0.1-1.0 ms) yield and instantaneous (for example 0.1-1.0 ms) return to the previous braking/tensioning in the event of an irregularity/knot occurring on the, even rapidly, passing yarn and/or an instantaneous response to one or more controls for modifying the braking or tensioning force of the system during one and the same yarn drawing-off (machine cycle stroke) from the body.
In one embodiment, a clamping member is arranged to operate in the extension of the longitudinal center axis of the storing body and effects its clamping action by means of an actuation surface/actuation part whose cross-sectional area is considerably reduced in relation to the cross-sectional area of the storing body at its yarn-storing peripheral surface. Another feature in this respect may be that the counterstay surface/counterstay edge has an external diameter which is considerably reduced in relation to the diameter of the storing body at the yarn-supporting part. In a preferred embodiment, the external diameter of the counterstay surface/counterstay edge is about 50% or less of the said diameter of the storing body. In certain embodiments, it is also important to keep the external diameter of the clamping member low, and in one embodiment the maximum external diameter is about 50% or less of the said diameter of the bearing body. In one embodiment, the control unit and the clamping unit are arranged in order to allow the clamping member to effect a variation of the clamping force during the drawing-off process. In one embodiment, the variation is sinusoidal or a variation is provided which is adapted to the machine function for the machine on which the yarn feeder in question is used.
The actuation part of the clamping member can be designed with an actuation surface which is annular and forms an unbroken annular part or consist of a number of elements which are arranged close to each other and which together form a broken annular part. In one embodiment, the clamping member can form part of or be connected to a hollow cylindrical-shaped or essentially funnel-shaped part whose recess constitutes or forms part of an outlet part for the yarn. In addition, the clamping member can be designed so as to be able to bear in resilient manner against the yarn and the counterstay surface/counterstay edge during the whole of or parts of the drawing-off turn of the yarn from the storing body. In the case where individual resilient elements are used, these come into operation one at a time and successively during the unwinding turn in order to carry out their respective clamping functions. The clamping member can constitute, form part of or be connected to a movable actuation unit which is able to effect the variable function during rapid drawing-off processes, for example drawing-off processes of about 50-100 ms.
In the case where the funnel-shaped clamping member consists of a number of resilient elements which are arranged at the front/wider end of the funnel, the elements are preferably secured on the edge of the funnel, on the inside, or in the vicinity of the edge of the funnel. In this case, the free parts of the resilient elements extend towards the center of the clamping member where they press the yarn against a preferably outwardly curving counterstay surface which is situated on a part of the storing body. The last-mentioned part can consist of a ring made of wear-resistant material, for example ceramic. The resilient elements can have the shape of laminae, "fingers", leaves, etc. At their first ends, the resilient elements are attached to or integrated with an annular part which forms a common part together with the elements. The annular part forms securing members which can be secured in the hollow cylindrical-shaped or funnel-shaped member. In the case of the funnel-shaped member, the cone-shaped part of the funnel can consist of one or more resilient elements which, in the clamping function, are pressed against the yarn and the counterstay surface/counterstay edge. The last-mentioned surface or edge can in turn be arranged on a part arranged on the storing body. This can be either rigidly arranged in the storing body or displaceably/resiliently arranged in the same. In a further exemplary embodiment, the part in question is moreover resilient in itself. In the case of a tubular displaceable/resilient part in the storing body, the displaceable resilient part is mounted in a storing housing arranged in the storing body. In the storing housing, the displaceable/resilient part can be pressed in counter to the action of a first spring member. The storing housing and the displaceable/resilient part are adjustable in order to permit adjustment of the spring force obtained from the first spring member. In order to obtain the said adjustment, the storing housing is arranged rotatably in the storing body. The first spring member is arranged between an inner support member and an inner surface of the displaceable or resilient part. The support member can in turn be displaceable in the longitudinal direction of the storing body, and the displacement can be effected with the aid of rotational movements of the storing housing.
In one embodiment, the clamping member and/or the resilient element/resilient elements is/are displaceable relative to the storing body/part by means of a control unit which operates by means of electrical energy or gas and/or liquid media. In the case of a number of controllable resilient elements, these can be controlled individually or in unison. In the case of individually controllable elements, these can be allocated controls which give simultaneous clamping forces of essentially the same magnitude and/or clamping forces which vary gradually along the periphery of the unwinding turn. The activation of the resilient elements can be seen as a pulsating actuation function moving around the periphery. This actuation function can be arranged in coordination and asynchronously or synchronously with the yarn drawing-off/yarn drawing-off function. The actuation function can thus operate keeping ahead or trailing behind in relation to the yarn drawing-off function.
In one embodiment with a funnel-shaped clamping member with resilient elements in the cone-shaped part, the latter is connected to or integrated with a yarn carrier tube which extends through a coil. The relative longitudinal displacement movements of the funnel-shaped member in relation to the storing body are effected with the aid of electrical control signals applied to the coil. In this case, a second spring member is used which acts on the outside of the cone-shaped part and is designed to serve as a return spring for the modulation movements of the clamping member generated by means of the electrical control signals.
The longitudinally displaceable clamping member is arranged with an adjustment member by means of which the initial position of the clamping member can be adjusted relative to the storing body. The adjustment member can be manually or automatically actuated. In one embodiment, bellows members are used, and individual resilient elements can be arranged in association with the said bellows members. In a first embodiment, the resilient elements are secured to or in the bellows members at their first ends, in order to be able to drag against the yarn with their free parts and to press the yarn against the storing body or the part related to the latter. In one embodiment, the bellows members can be arranged on a wall or equivalent unit (disc-shaped part) which centrally supports the outlet part. The latter is thus separated from the clamping member. The wall or equivalent part can be adjusted relative to the storing body in order to obtain an initial position.
In the case of a displaceably/resiliently arranged part in the storing body, the said displaceable or resilient part can comprise a hood-shaped member. The latter can comprise an outer annular flange projecting from the member and of comparatively small diameter. The clamping member works against the flange with an actuating surface of correspondingly small diameter. The hood can comprise a projecting flange which serves as a stop member in the bearing of the part in the storing body. A small mass is of importance for the clamping member, and a mass of, for example, at most about 20 grams is used for the movable part in the clamping member. The secure clamping forces may be of the order of magnitude of 0-200 cN.
In one embodiment, the invention can be regarded as being characterized, inter alia, by the fact that the resilient elements are arranged in such a way that they can be tilted about bearing points, from whose first sides there project one or more actuating parts actuable by the control unit for the tilting movements of the resilient elements, and from whose second sides the resilient elements project in order to produce the said pressing. As a supplement or alternative to these features, the invention can be regarded as being characterised by the fact that the resilient elements are actuable from the control unit with a control actuation function pulsating around the periphery of the storing body and synchronous or asynchronous with the unwinding function of the yarn.
In further developments of the inventive concept, it is proposed that the actuating part will consist of an annular element from whose inner edge or inside the resilient elements project. The annular element can in this case be disc-shaped and arranged edgeways in the element's own plane. The resilient elements extend from the annular element inwards towards the centre and at small angles in relation to the plane and/or small angles in their own plane. The annular element has recesses for the tilting function, and the recesses in question can be distributed uniformly along the periphery of the annular element.
The resilient elements can be arranged individually or in groups around the periphery and each resilient element or group of resilient elements is allocated its control unit part which effects an individual actuation of the element or group of elements. In this case, the control unit parts can be controlled by a selector member, for example a register member, which successively connects the control unit parts depending on the movement/function of the selector. In this way, the pulsating control actuation function is obtained. In the case of an asynchronous control actuation function, this can operate with trailing behind or lying slightly in advance of the drawing-off function. The control unit is arranged to give a varied control function so that the pressing force, during the drawing-off of the yarn, varies sinusoidally or exhibits a variation which is adapted to the textile machine (gripper machine) for which the yarn feeder is intended. The control unit can operate with electrical control functioning or with some form of control media, for example gas and/or liquid. In the case of gas and/or liquid, use is made of hose parts, bellows members which are arranged beside each other around the section in question. The hose parts, the bellows members etc. are activated by the control unit successively during the pulsating actuation function so that the activation of each spring element or group of spring elements is effected.
According to the invention, there may be cooperating brake units and a brake or detaining unit. The first brake unit has a small mass and acts against a counterstay surface or counterstay edge on or at the nose of the storing body or a part on or at the nose of the storing body. The first brake unit can in this case have a small external diameter (permits small mass). A second brake or detaining unit acts against a second counterstay surface or counterstay edge which can be situated at the large diameter of the storing body, i.e. at the yarn-supporting part. The first brake unit effects at least the principal yarn-tensioning characteristic for the yarn part running out from the first brake unit. The second brake or detaining unit is intended to serve as a preliminary braking which may be deactivated at the start of and during the major part of the drawing-off process. Alternatively, in this part of the drawing-off process, it can operate with a smaller basic braking, which makes only a small contribution to the yarn-tensioning characteristic. During the final part, the second unit will have a braking or detaining effect on the yarn, which prevents slackening of the yarn part between said first and second units. The prevention of slackening eliminates any unacceptable entangling and/or characteristic-affecting tendencies.
In different embodiments, the first and second units are physically separated or physically coordinated. In addition, they can be controlled individually or in coordination from one or more higher-ranking control units for one or more yarn feeders and/or the textile machine in question.
The invention in the form of a brake arrangement, which can be used on a yarn feeder with a storing body for yarn and which, during the drawing-off of the yarn, permits modified or varied brake functioning on the yarn, even during rapid drawing-off processes, can alternatively use a first and second brake unit (detaining unit) or only the second brake unit (detaining unit). In the last-mentioned case, the invention can be regarded as being characterized, inter alia, by the fact that the second brake unit consists of or comprises an annular member and, associated with this, one or more feather-, finger- or bristle-shaped elements which extend from the annular member and inwards, if appropriate slightly inclined in and/or in relation to the plane of the annular element, towards the centre of the annular member. In a preferred embodiment with an annular member and associated elements, the latter are preferably arranged displaceably in the longitudinal direction of the storing body in order to permit reduction or increase of the pressing force of the elements against a counterstay surface or counterstay edge situated on the storing body, and in this respect of the pressing of the elements against the yarn when the latter passes the respective elements and the second counterstay edge/counterstay surface. The said elements can be arranged per se displaceably in the annular member so that the variable pressing force occurs. This displacement can be obtained with the aid of actuation members, in the form of electromagnet functioning, bellows or hose member functioning which operates with media in the form of gas, liquid, etc., and so on.
In a further embodiment, the second brake unit can consist of one or more pole body members with one or more leaf- or wirespring-shaped elements which can be secured at their respective first ends on respective pole body members which are arranged separately or are physically connected to each other to form an annular unit around the second counterstay surface or counterstay edge. Each pole body member can have a concave inner surface directed towards the second counterstay surface or counterstay edge, at which inner surface each resilient element is arranged in such a way that, from its first secured end, it extends with its free part downwards over the second counterstay surface part or counterstay edge part in question, where the said free part forms a part which can cooperate directly with the yarn when the yarn passes the said free part during the drawing-off process. The free part can also be designed with an angled part which forms a stop member which, when the free part bears against the counterstay surface or counterstay edge, comes into cooperation with the latter via a recess. In the case with a number of pole body members, which in this case are preferably distributed uniformly around the second counterstay surface or counterstay edge, the pole body members can be controlled individually or jointly from the said control unit/control units. With the pole body member(s) deactivated, each leaf- or wirespring-shaped element effects a deceleration and/or stop/detaining function on the yarn, and with the pole body member(s) activated, there is an elimination or reduction of the deceleration function and the stopping or detaining function which may optionally follow it.
Each free part of each leaf- or wire-shaped element extends in an arch or curve over an allocated part of the second counterstay surface or counterstay edge. In this case the length of the element can substantially exceed the length of the associated concave surface and can, for example, be up to twice as long as this. Alternatively, the length of the element is substantially equal to the length of the concave surface of the pole body member. Each pole body member can have a rectangular, square or U-shaped cross-section, etc. The second brake or stop/detaining member comprises one or more bearing members arranged spaced over the second counterstay surface or counterstay edge for pin- or needle-shaped members which are designed to act in a radial direction or in a direction which is inclined in relation to the radial direction, seen in the cross-section of the storing body. The pins or the needles act in a direction towards and away from the second counterstay surface or counterstay edge. The said pin- or needle-shaped members assume a first position in which the yarn passing under the pins or the needles moves freely from the pins or the needles, and a second position in which the yarn moves only partially freely (is braked) or is stopped. The taking-up of the second position from the first position can be effected successively. The actuation from the first position to the second position, or vice versa, can take place counter to the action of a spring function or elasticity function in each needle or spring or in a spring member which acts on each needle and spring. Each needle and spring can therefore spring back from its respective actuation positions as soon as the actuation ceases. The mass in each pin and needle is very small, and the bearing can also be designed substantially friction-free. The pins or the needles can lie loosely in their bearings in their non-actuated positions, the result being that they do not exert any real effect on the yarn, but instead the latter can pass the pins/needles and, upon passing the respective pin/needle, can push the latter aside. Upon application of the actuation of the pins/needles, the latter are forced by the actuation force against the counterstay surface/counterstay edge and can exert their braking effect successively (gradually) or directly. The actuation members can consist of electromagnets, one or more hoses which operate with liquid or gas media, etc. The actuation of each needle or pin can be effected via resilient elements which provide the successive braking function. The pins/needles can be designed with head-shaped elements.
In a further embodiment, the second brake or detaining/stop member consists of a part which extends around the second counterstay surface or counterstay edge and can be deformed upon actuation, which can be produced, for example, by means of a piston member, magnet member, etc. Upon application of the actuation, two brake or stop parts occur between the second counterstay surface or counterstay edge and the deformable member. In a further embodiment, the second brake unit comprises one or more brake bands or brake wires which are positioned opposite associated parts of the counterstay surface or counterstay edge. The bearing points for the brake band parts or the brake wire parts can be actuated by means of motors effecting rapid rotational movements.
In one embodiment, the first brake member is provided with one or more rearwardly-extending finger- or wire-shaped elements. The ends of the latter extend over the second counterstay surface/counterstay edge where the ends are arranged, as a function of actuations, for example from one or more magnetic fields, to come into braking or detaining/stopping cooperation for the yarn with the second counterstay surface/counterstay edge.
The feature which can be regarded as characterising one embodiment of the invention is that the surface-supporting parts have external diameters or peripheries which are substantially reduced, for example 10-40%, in relation to the diameter of the thread store.
In further embodiments of the inventive concept, more details are given of the construction of the brake. An important fact in this respect is that it will be possible to use low-weight spring members. In the case of a manually adjustable brake, use is made of a unit which comprises a sleeve or a housing which contains a rotatable screw and a nut. The screw can be subjected to manual rotational movements and the nut is designed in such a way that, upon movements of the screw, the nut executes longitudinal displacement movements in relation to the first surface-supporting part. The nut can constitute a support member for a spring member arranged between the second surface-supporting unit and the support member. The pressing force, with which the first and second surface-supporting parts bear against each other, can therefore be determined with the aid of rotational adjustments of the screw. Said adjustments are advantageously carried out in such a way that thread tensions in the range 0-100 grams are obtained. In one embodiment, the nut can be provided with a guide member which prevents rotational movements of the nut when the screw is turned. The guide member can run in a slot in the sleeve or housing, and the slot and the support member can form indicating members for the longitudinal displacement position of the nut in the sleeve/housing. Said longitudinal displacement position therefore constitutes a measure of the pressing force between the first and second surface-supporting parts.
The brake can also comprise a rough adjustment, by virtue of the fact that the unit as a whole is designed so that it can be adjusted roughly in the direction towards and away from the first surface-supporting part.
In a further embodiment, use is made of a so-called controlled unit for brake/thread-tensioning generation which can operate with great speed and sensitivity and can, during one and the same thread draw-off, for example weft pick, vary the pressing force of the second surface-supporting part against the first surface-supporting part and thereby vary the thread tensioning. Said actuation unit operates with voice (loudspeaker) coil functioning which in a known manner comprises a magnet member arranged in an iron core. In addition, there is a coil which receives electrical controls and, as a function of these, executes longitudinal displacement movements. The coil is connected to a diaphragm-suspended hub, to which the second surface-supporting part is also connected. The movements of the coil can in this way be transmitted to the second surface-supporting part as a function of said electrical controls. The unit comprises a bearing tube for the second surface-supporting part. The tube is suspended in one or more diaphragms. In one embodiment, the first surface-supporting part is arranged in said frame. Alternatively, the part can form part of said frame. Both surface-supporting parts have the shapes of a disc/plate having a straight and a curved section. The discs can be made to bear against each other at said straight sections, and the curved sections together form a large receiving opening for the incoming thread part.
In one embodiment, the first surface-supporting part is arranged in the thread-storing drum in the thread-storing member. Alternatively, the part can form part of, i.e. constitute an integrated part of the said drum. Both surface-supporting parts can have the shape of a disc/plate having a straight and a curved section. The discs in each part can be made to bear against each other via said straight sections, and the curved sections together form a suitable inlet opening for the incoming thread part.
In one embodiment, there is parallelism between the brake discs used. The brake acts by means of the brake discs exerting friction against the thread/yarn passing between them. In an embodiment intended to be able to produce a stable (constant) yarn tensioning, it is important that the pressure between the discs should be as constant as possible over the entire periphery of the brake. This necessitates a parallel and centered adjustment of the discs and their attachment. Since the number of intermediate/adjacent construction elements (for example the yarn feeder jib, in which the counter-brake disc is arranged) in the thread-storing member/yarn feeder is high, there is from the point of view of manufacturing and assembly a complicated problem which has hitherto been difficult to solve.
In a further embodiment, it is proposed to arrange a cavity for drawing the thread/yarn through the brake.
The problems mentioned above are solved in a technically simple but nevertheless satisfactorily functioning manner. The brake function can be integrated with the outlet channel part, which results in advantages from the point of view of construction. The diameter of the brake-effecting unit can be made small. The mass used upon braking can be made small, which is a precondition for rapid regulation of the clamping function and permits the desired rapid variation during the short drawing-out processes for the yarn.
By means of the invention it is possible to retain the advantages by using the rotational movement of the yarn upon drawing-off from the bearing body. Above all, the brake surfaces are effectively kept clean as a result of the sweeping movement. This provides large friction surfaces, which result in good cooling and wear-resistance. If the brake surface is designed as a finger-shaped brake surface, knots and irregularities in the yarn can easily pass without any great increase in tensioning, by virtue of the fact that it is only small masses which have to be lifted. By means of selecting the direction of the finger-shaped elements, it is possible to obtain easily a suitable yarn contact, with simultaneous cleaning by means of lint, particles etc. being transported off in the direction of the fingers. The resilient elements can be made light and of simple construction in order to permit, inter alia, replacement upon wearing and adaptation to different brake requirements. By using a longitudinally displaceable adjustment arrangement, it is possible to achieve a simple arrangement for adjusting the magnitude of the basic brake action, and the adjustment arrangement can also be designed such that brake element replacement, threading etc. are facilitated. The brake elements can be arranged such that a movement can be permitted for any eccentricity in the attachment and the storing body suspension. In the cylindrical yarn outlet part is secured the movable part of the manoeuvring unit, which can have the shape either of a coil or permanent magnet. Around the movable part the magnet coil or the permanent magnet is attached. By means of the electrical control arrangement, the manoeuvring cone can be displaced in the axial direction and exert a force against the coil body which, for the yarn, produces a clamping force between the brake element and the wear ring of the coil body cone. The bellows members in question can operate with air pressure in the bellows, which presses the brake elements against the wear surface of the storing body cone and produces an increased clamping force/brake effect. A control eye placed in the attachment can be used, and the risk of lint accumulation can be eliminated by using a control cone arranged between bellows and brake element.
By means of the measures suggested above, a yarn brake can moreover be built with the desired yarn-braking function.
The control by means of the control unit can be carried out in a manner known per se, and the desired variation of the yarn-actuation can be built in from the control point of view and from the mechanical or electromagnetic point of view.
A coil which thus acts essentially on the cylindrical part of the storing body can conceivably be designed in such a way that a utilised brake collar flange can be designed to be acted upon by, for example, one or more pneumatic elements. Each joint can be designed, for example, simply by punching out holes or slots in the brake collar, which holes or slots can be passed over pins or tips in the suspension ring over the peripheral surface of the storing body of the yarn feeder. The ring or the member which is arranged over the peripheral surface of the yarn-storing part is preferably designed as a closed channel which can comprise one or more air hoses or equivalent. The ring or the unit bearing the air hose is preferably arranged adjustably in the longitudinal direction of the bearing part in order to permit basic tensioning and opening for threading of the yarn between the brake elements.
The finger-shaped brake surface means that knots and irregularities in the yarn can pass more easily, without any great increase in tensioning, by virtue of the fact that it is only small masses which have to be lifted. By using finger-shaped brake diaphragms, the direction of the fingers can be adapted for suitable yarn contact, and cleaning takes place easily by means of lint etc. being transported off in the direction of the fingers. The brake elements are light and can be designed for easy replacement upon wearing and adaptation to different brake requirements. By using a bearing housing for hose parts, the hose can be divided up into a number of partial hoses which are activated successively in a sequence determined by a control unit, the result being that the desired pulsating actuation can be achieved.
A brake function operating for different application cases can be obtained. It is also possible, for example, to use two brakes which are controlled in relation to each other in such a way that a slight preliminary braking is obtained for the brake which effects the actual braking, in which respect it is ensured that the yarn part between utilised brakes is at all times tensioned. The preliminary braking can alternatively consist of a constant light braking, and this can be obtained in different ways according to the invention. At high yarn speeds, the fixed preliminary braking can be replaced by a variable light braking.
At, for example, 75% of the diameter D in question, the particularly important advantage remains that the brake surfaces are at all times kept effectively clear of lint and the like during the thread drawing-off as a result of the "rotating" movement of the thread or yarn in the brake when using the structural design which, independently of chosen diameter relationships, can perhaps be best described or defined as the output brake consisting of a plate brake arranged at the drawing-off end of the thread-storing member, transverse to the direction of linear movement of the thread, in which the second plate in the plate brake (=the second surface-supporting part) cooperates with the first plate, or alternatively directly with the end surface of the yarn-storing member (=the first surface-supporting part) for clamping of the thread or the yarn which, during its drawing-off from the yarn-storing member, runs radially inwards towards the centre of the "plate brake", in which respect this radial entry on account of the drawing-off movement constantly migrates clockwise or anticlockwise (depending on the direction of drawing-off) in the brake, and where the thread or the yarn thereafter runs out from the brake and away from the yarn-storing member through a passage in the centre of the second plate (=the second surface-supporting part).